1. Field of the Invention
The present invention relates to devices used in the assembly of electronic circuit boards, and particularly, to automated devices for mounting electronic components on printed circuit boards.
2. Prior Art
Robots for automated mounting of electronic components on printed circuit boards are conventionally known. Components to be mounted are generally manipulated using multiple grasping mechanisms, for example, one for transistors, one for integrated circuits, one for resistors, etc., with movement of each grasping mechanism controllable in three dimensions through operation of a separate driving mechanism for the x-axis, y-axis and z-axis for each grasping mechanism. Most commonly, components are supplied to a predetermined location in proximity to the board under assembly, and through use of a control program which supplies Cartesian coordinate data along with other control data, the various grasping mechanisms move sequentially between the component supply point and an appropriate location on the circuit board where the currently grasped component is then seated.
After a component is thus seated on the circuit board with each lead passing through a respective lead hole, a mounting mechanism bends each lead at a point after it passes through the lead hole so as to prevent the component from falling out prior to soldering. As with the grasping mechanisms, different mounting mechanisms are used for the various different types of components, and each is controllable in three dimensions based on Cartesian coordinate control data. Thus, the robot must control and coordinate multiple grasping mechanisms and mounting mechanisms.
Conventional robots for automated circuit assembly as thus described have the following limitations:
(1) At each station on an assembly line where such a robot is employed, generally the robot at each station is the same. In other words, every robot must be capable of handling every type of component, and capable of mounting nearly any number of components at a given station. Thus, for example, the robot used at a station where one resistor is mounted is the same kind of robot at stations where multiple different components are mounted. For this reason, quite commonly, a very expensive, multifunctional robot is used at a station where only limited assembly is required, which is decidedly uneconomical.
(2) Control of multiple grasping and mounting mechanisms in three dimensions is exceedingly complicated. Thus, unless very expensive high speed computational devices are used for control, control data is supplied at a low rate and assembly is therefore time consuming.